1. Field of the Invention
The present invention relates to a method of manufacturing steel sheets coated with Znxe2x80x94Fe alloy which are used in producing a body frame and a chassis of an automobile, and more particularly to a method of manufacturing electrogalvanized steel sheets coated with Znxe2x80x94Fe alloy having maximized corrosion resistance and simplified process by optimizing deposition parameters such as temperature, pH, electric current density of an electrolyte consisting of zinc sulfate hydrate, iron sulfate hydrate, ammonium sulfate and potassium chloride as well as the thickness of a coating layer.
2. Description of the Prior Art
It has been well known to use steel sheets coated with zinc alloy in body frame or chassis of automobiles due to their improved mechanical properties in molding and welding compared to those coated with pure zinc.
In manufacturing conventional steel sheets coated with Znxe2x80x94Fe alloy, most of composition control has been mainly depended on the direct control by changing the composition of each electrolyte and the effect of anomalous codeposition by adjusting the electric current densities has been rarely considered. Moreover, it has been shown that loading of excessive current densities only to improve the productivity of steel sheets often resulted in both the waste in electric power and the over-consumption of iron.
An object of the present invention is to provide a method of manufacturing steel sheets coated with Znxe2x80x94Fe alloy having maximized corrosion resistance and simplified process so as to be used in producing body frame and chassis of automobiles by optimizing deposition parameters such as temperature, pH, electric current density of an electrolyte consisting of zinc sulfate hydrate, iron sulfate hydrate, ammonium sulfate and potassium chloride as well as the thickness of a coating layer.